Microstructure and Mechanical Properties of High Vacuum Die-Cast AlSiMgMn Alloys at as-Cast and T6-Treated Conditions

Abstract

Al–Si–Mg based alloys can provide high strength and ductility to satisfy the increasing demands of thin wall castings for automotive applications. This study has investigated the effects of T6 heat-treatment on the microstructures, the local mechanical properties of alloy phases and the fracture behavior of high vacuum die-cast AlSiMgMn alloys using in-situ scanning electron microscopy (SEM) in combination with nano-indentation testing. The microstructures of the alloys at as-cast and T6 treated conditions were compared and analyzed. It is found that the T6 heat treatment plays different roles in affecting the hardness and the Young’s modulus of alloy phases. This study also found that the T6 heat treatment would influence the failure modes of the alloys. The mechanisms of crack propagation in the as-cast and T6 treated alloys were also analyzed and discussed.

Low- and High-Pressure Casting Aluminum Alloys: A Review

“…In a study of the effect of T6 heat treatment on the alloy AlSi11MgMn, Liu et al [39] observed a decrease in UTS, while the elongation increased for alloys produced by VHPDC. In this alloy, the microcracks formed near the large α-Fe intermetallic and not due to the eutectic Si particles.…”

Effect of novel grain refiner and Ni alloying additions on microstructure and mechanical properties of Al-Si9.8-Cu3.4 HPDC castings – optimization using Multi Criteria Decision making approach

“…Mechanical properties of the aluminum-silicon alloys, in particular the tensile strength, ductility, hardness, and fatigue, are * E-mail: kchapparao@gmail.com strongly dependent on the dendritic structure, and on primary Al α-grains in the respective microstructures [3,4]. Kori et al [5] observed that grain refinement is the most effective process to achieve homogeneously distributed small equiaxed grains, and in addition, following this process results in a high strength-to-weight ratio, excellent castability, and other desired properties [6][7][8].…”

Comparison of Porosity of Casts Produced by HPDC and VPDC Technologies

“…During the transition of the melt through then cross-sections and complex shapes of the cast, more significant mixing of gases and vapors with melt occurs [Cao 2019]. One of the possibilities to prevent mixing of the melt with gases is a suitable design of the gating system, starting with the correct design of the runners, through the design of the ingates to the correct design of the ventilation system [Meethum 2017, Otsuka 2014]. Another possibility of elimination of the porosity in casts is the correct setting of technological parameters of the casting cycle [Pasko 2014].…”

“…On the other hand, high pressure values support faster wearing off the mold and increased demands on design and quality of the mold material [Nova 2012, Ruzbarsky 2014. In conventional HPDC technology i tis necessary to find a compromise between the design of the gating system and the setting of technological parameters of casting with respect to the melt flow regime through the runners and perfect discharge of the gases from mold cavity in front of the advancing melt stream [Liu 2018]. A progressive development of the HPDC is the incorporation of a vacuum device into the process to extract gases and vapors from the mold cavity in front of the advancing melt stream.…”

“…The low pressure in the mold cavity allows the molten metal to flow even through the blind recesses and the designed chamfers of the cast. Sufficient vacuum allows the melt flow face to proceed freely through the gating system without creating vortices and thus entrap the gases in its volume [Liu 2019, Szalva 2019]. The fundamental differences in HPDC and VPDC technology are shown on Fig.…”